how to test positive and negative speaker wires with multimeter

The quality of your speaker’s audio output is one thing you don’t take for granted, especially for music lovers. 

Sometimes you may want to make an upgrade to the whole sound system, change only speakers, or customize your listening experience to what makes it more wholesome. Whichever of these, the quality of the final audio output depends on how the speaker components are wired.

This article takes you through all you need to know about speaker polarity, including how to test whether wires have been connected appropriately and the implications of bad wiring. Let’s get right in.

What Is Speaker Polarity And Why Is It Important

Your speaker polarity relates to the negative and positive wiring of your speakers and is important within your car’s sound system. 

Every component within the sound system runs through the amplifier. This includes RCA/phone cables running to the radio head unit as well as incoming power cables, ground cables, and, of course, wires coming from your speakers. 

Some car sound systems are more intricate than this as they include more components and feature a more complex series of cables and wiring. Nonetheless, this basic setup remains core to the crucial functions of your sound system.

Two wires run directly from your speakers and these are either positive or negative. Ordinarily, where speakers are used individually, there isn’t much to worry about as they work regardless of wiring.

speaker and multimeter

However, where you make use of two speakers in the same sound system (which is the common setup) there may be sound distortions or cancellations. Additionally, as you are required to hook your speakers up to an amplifier for better audio quality, you are also expected to experience sound distortions or interruptions. This is because the amplifier has dedicated positive and negative terminals.

How do you then determine which wire is positive and which wire is negative? There are multiple methods to do this, however, the best and most infallible is the use of a multimeter.

How To Test Positive And Negative Speaker Wires With A Multimeter

To test the polarity of your speaker wires, you place your negative (black) and positive (red) multimeter leads on each wire. If the multimeter reads positive, then your leads are connected to equally polar wires, that is, the red positive probe is connected to the positive wire, and vice-versa. 

Further explanation on this would be made below.

A digital multimeter is a tool used to test out multiple electronic components and with multiple units of measurement on it. When testing out your speaker wires or anything in your car, you want to set your multimeter to DC voltage.

Plug in your positive (red) and negative (black) test leads and observe the following steps.

  1. Disconnect All Components

Before testing out anything, you ensure that you unplug all the speaker components from your sound system. This is to ensure your safety from electrical hazards.

One best practice is to take a picture of the sound system before disconnecting any of the components. This picture is then used as a guide when connecting components back so that you don’t make any mistakes.

  1. Place Your Leads On The Speaker Wires

There are two wires coming from your speaker terminals. A lot of times, these wires are not distinguishable, so you don’t know which is positive or negative.

What you want to do now is to connect your negative and positive multimeter lead to each of the wires. You place the positive red lead on one wire, place the negative black lead on the other, and check out the reading produced by your multimeter. This is where you make a decision.

  1. Check For A Positive Or Negative Reading

If the positive lead is placed on the positive wire and the negative lead is equally placed on the negative wire, the digital multimeter shows a positive reading.

On the other hand, if the positive lead is placed on a negative wire and the negative lead is placed on the positive wire, the multimeter shows a negative reading.

Either way, you know which wire is positive and which wire is negative. You then mark them appropriately for when next you want to make connections with them.

While placing your leads on the wires, making use of alligator clips makes the whole process easier. A tape is also useful for marking your wires.

  1. Reconnect Components Back Into The Audio System

After appropriately tagging your wires as positive and negative, you then reconnect all speaker components back into the audio system. The picture you have previously taken may prove useful here.

As mentioned before, there are other ways to check the positive and negative wires on your speakers.

Checking Polarity Using Battery

The speaker wires can be checked by simply using a low-voltage battery. Here, you take note of the positive and negative points on the battery you want to use and connect the wires from your speakers to each.

speakers and battery

If the speaker cone pushes out, then the positive and negative wires are connected appropriately. If the cone pushes in, then the wires are being mixed up. 

Either way, you also know which wire or terminal is positive or negative. In case you are not clear, this video helps shed light. 

Checking Using Color Codes

One other way to determine your speaker polarity is to make use of the appropriate color coding relating to the wire. 

The positive wire is usually coated in red and the negative wire is usually coated in black. However, this is not always the case as they could be mixed up or just coated with the same color. Check your user manual in case it is a new speaker.

This method is not always actionable.


Identifying the polarity of your speaker wires isn’t a hard nut to crack. You simply check for color codes and, in case these are not present, you check the movement of speaker cones with the use of a battery or readings with the use of a multimeter.

Whichever method you use, making the right connections assures you of the best sound quality you could get from your sound system.

Frequently Asked Questions

How Do You Know Which Speaker Wire Is Positive And Negative?

To know which speaker wire is positive or negative, you either use color codes or use your multimeter to check for polarity. A positive multimeter reading means the leads are connected to the appropriate wires. That is, the negative black probe is connected to a negative speaker wire and vice versa.

How Can You Tell If Speaker Polarity Is Correct?

To tell if speaker polarity is correct, you place your multimeter leads on your two speaker terminals and wait for a reading. A positive reading means the speaker’s polarity is correct.

How Do I Know If My Speakers Are Wired Backwards?

To know if your speaker is wired backward, you place your multimeter leads on each wire from the speaker’s terminals. A negative multimeter reading means the speakers are wired backward.

What Does A and B Mean On Speakers?

When using A/V receivers, A and B speakers serve as different audio output channels with different sets of speakers hooked up to them. You either play audio through speakers on channel A, play through speakers on channel B, or play through both channels.

How Do You Tell Which Speaker Is Left And Right?

To tell which speaker is left or right, the best practice is to do a sound test. You play test audio through the speakers and listen for where the appropriate audio outputs are coming from.